A dependent is usually defined as someone you support or take care of. Generally speaking, a dependent could be a child, a relative, or even a friend. However, for tax purposes, not everyone you take care of qualifies as a dependent. The IRS has come up with a few rules to help you determine who a qualifying child or relative is. In this article, we'll walk you through those rules.

Rules for Qualifying Children as DependentsAccording to the IRS, the uniform definition of a child is a natural child, an adopted child, a stepchild or an eligible foster child. In addition to meeting this definition, a dependent who is being claimed as a qualifying child has to meet all four of the following tests:

The Relationship Test: A qualifying child can be a sibling, a step-sibling, or a descendant (a grandchild, a niece, a nephew, and so on), as well as other relationships mentioned above.

The Residency Test: a qualifying child has to have the same residence or "principal abode" as the taxpayer for more than half the year. However, there are exceptions for temporary absences; for instance, if a qualifying child is away from home because of custody arrangements, school, an illness, military duty, or business, that child will still meet the residency test.

The Age Test: A qualifying child has to be either under the age of 19 or both under the age of 24 and a full-time student for at least five months of the year. There is no age limit for someone who is permanently and totally disabled.

The Support Test: The individual who is being claimed as a dependent must not have provided more than half of his or her own support. If you're trying to claim an individual who has a job and partially takes care of him or herself, you have to make sure that you can prove that during the year, he or she was responsible for 50% or less of his or her total support.

Qualifying Child Tests and Various CreditsThese four tests are the basic tests for a qualifying child, but, depending on the tax credit you're trying to claim, there are additional tests that must be met:

Dependency Exemption and Head-of-Household Filing Status: The individual being claimed as a dependent must meet the four basic tests in addition to two other ones:

Citizenship Test: A qualifying child for the dependent exemption must be a U.S. citizen, U.S. national or a resident of the United States, Canada or Mexico.

Joint-Return Test: If a dependent is married and files a joint return with his or her spouse, the dependent does not count as a qualifying child. The only exception to this rule is if the dependent and his or her spouse are not required to file taxes and only do so to get a refund.

Child and Dependent Care Credit: The individual being claimed as a dependent must meet the four basic tests, but there is a modification when it comes to the age test. For the child and dependent care credit, the dependent must be under age 13 unless the individual is permanently or totally disabled.

Child Tax Credit: A child is your qualifying child for the child tax credit if he or she meets the four basic tests except for the age test: The child must be under age 17 and must be claimed as your dependent.

Earned Income Credit (EIC): A qualifying child for the EIC has to meet only three of the basic dependent tests: the relationship, age and residency tests. In addition to meeting those three basic tests, the child must have lived with you in the U.S. for more than half the year.

Tie-Breaker Rules for Determining a Qualifying ChildIf there is ever a situation where a child qualifies as a qualifying child for two taxpayers, the following tie-breaker rules developed by the IRS should be used to determine which taxpayer claims the tax benefits:

When two taxpayers cannot determine who will claim a child, the child will be the qualifying child of the parent.

If both taxpayers are the child's parents and they do not file a joint return, the parent who can claim the child will be the parent with whom the child lived for the "longest period of time during the year." (For more, see Taxing Times For Divorced Parents.)

If it turns out that the child lived with both parents for an equal amount of time, the parent with the highest adjusted gross income (AGI) can claim the tax benefits.

If none of the taxpayers is the child's parent, the taxpayer with the highest AGI can claim the benefits.

Rules for Qualifying RelativesSome dependents don't fall into the category of a qualifying child but may meet other standards and tests set by the IRS, which enables you to get certain tax credits. In addition to the joint return and citizenship tests, a qualifying relative has to meet the following four rules:

Qualifying Child Test: To be a qualifying relative, the individual cannot be a qualifying child for anyone else. In other words, a dependent is only a qualifying relative if he or she does not meet the qualifying child tests for you or another taxpayer.

Relationship Test: A qualifying relative can be a child or descendant of a child, a sibling, a step-sibling, a descendant of a sibling (a niece or nephew), a parent or step-parent, an ancestor of a parent (a grandparent, great-grandparent, etc.), an uncle or aunt, a father-in-law or mother-in-law, or an individual who lives with the taxpayer for the entire year, regardless of whether the individual is related to the taxpayer, as long as the relationship between the taxpayer and the individual does not violate local law.

Gross-Income Test: The dependent's income cannot be above a certain amount. In 2013, that amount is $3,900.

Support Test: For a dependent to be a qualifying relative, the taxpayer must have provided more than half of his or her support. Note the difference between the support test for a qualifying relative and a qualifying child. For a qualifying child, the taxpayer has to prove that the dependent (the child) provided half or less than half of his or her own support; for a qualifying relative, the taxpayer has to prove that the taxpayer provided more than half of the dependent's support.

The Bottom LineIf your dependent-care situation is not straightforward, determining whether an individual is a qualifying child or relative can be very confusing. If you can't determine who a qualifying child or relative is, or you find yourself in a situation where you can't determine who can claim a qualifying child or relative, contact the IRS at 1-800-829-1040 or contact your local IRS office.